A304733 - OEIS

%I #12 Dec 20 2021 05:27:42

%S 1,2,2,3,3,3,3,2,5,5,5,3,7,7,7,3,2,5,11,11,11,3,5,5,7,7,13,13,13,3,2,

%T 17,17,17,7,19,19,19,5,5,11,23,23,23,3,5,13,3,7,7,7,5,11,13,7,29,29,

%U 29,11,31,31,31,3,2,17,37,37,37,5,13,19,5,41,41,41,3,7,11,11,43,43,43,5,17,19,5,23,47,47,47,3,7,13,13,17,11,7,3,53,53,53,19

%N The largest prime factor of the n-th term of EKG-sequence: a(n) = A006530(A064413(n)).

%H Antti Karttunen, <a href="/A304733/b304733.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Ed#EKG">Index entries for sequences related to EKG sequence</a>

%F a(n) = A006530(A064413(n)).

%t ekGrapher[s_List] := Block[{m = s[[-1]], k = 3}, While[MemberQ[s, k] || GCD[m, k] == 1, k++]; Append[s, k]];

%t FactorInteger[#][[-1, 1]]& /@ Nest[ekGrapher, {1, 2}, 100] (* _Jean-François Alcover_, Dec 20 2021, after _Robert G. Wilson v_ in A064413 *)

%o (PARI)

%o A006530(n) = if(n>1, vecmax(factor(n)[, 1]), 1);

%o A304733(n) = A006530(A064413(n)); \\ Needs also an implementation of A064413.

%Y Cf. A006530, A064413, A064741, A304734.

%Y Cf. also A251103.

%K nonn

%O 1,2

%A _Antti Karttunen_, May 18 2018